Designed for ISW4, the Bowers & Wilkins Back Box BB-ISW-4 prevents wall shake and cabinet distortions that plague other designs. Back-box to optimize cabinet volume for the drivers and reduce acoustic bleed-through to other rooms.
In drywall construction, the back box increases sound insulation to adjoining rooms. It also provides the fire safety barrier sometimes required by building regulations to prevent any fire present in the wall cavity from spreading into the room. When used in solid construction, the backbox will define an appropriate working volume for the speaker which may need to extend beyond the boundaries of the wall frame.